The present invention relates to a robot which can recognize the presence, position and posture of an object to be handled by the robot and spacial circumstances within operating limits, this information being required for executing various operations such as assembly, inspection and adjustments by the use of the robot.
As exemplified in FIG. 1, robot vision for recognizing the position and posture of an object detects an image by installing an image detector 3 over a work table 1 and illuminating this work table from near the same by means of an illuminator 4. Upon the recognition of the position and posture of the object, a robot arm 2 operates in accordance with the information. This method can recognize the position and posture of the object on the plane of the table, but it cannot recognize the three-dimensional shape of the object. For example, regarding articles piled on the table, each article cannot be approached by inclining the robot arm in accordance with the inclination information thereof so as to agree with the grip surface thereof. Moreover, unless there is a clear contrast (difference in density) between the object and the work table, the position and posture on the plane of the table cannot be determined.
On the other hand, a system has been known in which a visual device is attached to the fore end of the arm of a robot so as to perform feedback. FIG. 2 shows an example of the system, wherein a weld line 5 along which a welding operation is conducted and a welding head 7 is tracked. A slit light projector 6 is mounted on the fore end of a robot arm 2, and projects slit light 8 on the weld line 5. An image detector 3 attached to the foremost end of the robot arm detects the image of the weld line and evaluates the position thereof, whereupon the robot arm is controlled so that the deviation of the weld line from a desired value may become zero. This system, however, detects the positions of the weld line and feeds them back at respective detection timings and cannot recognize the three-dimensional position and posture of the object.